The present invention relates to a laser printer, electrophotographic copier, facsimile transceiver or similar electrophotographic image forming equipment of the type having a charger for charging the surface of a photoconductive element to form a latent image electrostatically thereon. More particularly, the present invention is concerned with a device for removing ozone generated in the equipment due to the discharge of the charger.
In image forming equipment of the type described, a high voltage is applied to a charger to charge the surface of a photoconductive element before the formation of an electrostatic latent image. In the event of discharge of the charger, air reacts to generate ozone which is apt to deteriorate the photoconductive element. While such ozone has to be driven out of the equipment, letting it out in high density is harmful. In the light of this, the equipment is usually provided with an ozone removing device thereinside. Customarily, the ozone removing device for such an application has a fan and an ozone filter. The ozone filter is disposed in, for example, a duct included in the exhaust section of the equipment. While the fan discharges air from the equipment to the outside via the ozone filter, ozone contained in the air is adsorbed by the ozone filter. A problem with this kind of device is that the ability of the ozone filter sequentially decays as the amount of ozone adsorbed thereby increases and, therefore, the life of the filter expires soon. Moreover, it is difficult to see the adequate timing for replacing the ozone filter whose life is limited as mentioned above. Should the replacement of the ozone filter be delayed, much of the ozone would be driven out of the equipment without being removed. Such an implementation, therefore, does not meet today's severe restrictions on ozone density.
An agent container containing a volatile ozone decomposing agent is another conventional approach available for increasing the life of the ozone filter and preventing the dense ozone from flowing out of the equipment surely and stably over a long period of time. The agent container is disposed in the exhaust section of the equipment together with the ozone filter and made up of a container body and a lid having a plurality of small openings. The container body accommodates the ozone decomposing agent therein and has an open end, while the lid closes the open end of the container body and allows the volatile matter of the agent to flow down through the small openings thereof. Regarding the agent, use may be made of limonen in the form of gel.
The open end of the container body of the agent container is usually sealed by a single seal member such as a polyester film in order to prevent the agent from volatilizing through the small openings of the lid in the even of transport or storage. To use the agent container, the seal member is removed from the container body to uncover all of the small openings of the lid, and then the agent container is mounted on the exhaust section of the equipment.
The conventional ozone removing device described above has various problems left unsolved, as enumerated below.
(1) The ozone filter and the agent container are fabricated independently of each other and mounted on different portions of the duct, so that the exhaust section and, therefore, the entire equipment is complicated in construction. In addition, mounting and dismounting the ozone filter and agent container one by one is troublesome. Moreover, the container body containing the ozone decomposing agent cannot be fully hermetically sealed.
(2) As the agent volatilizes with the lapse of time, the outer periphery thereof contacting the inner periphery of the container body comes off and drops. Then, the agent blocks the openings of the lid and thereby noticeably lowers the rate of volatilization of the agent, compared to the condition wherein the agent is spaced apart from the openings. This degrades ozone decomposition available with the ozone removing device.
(3) The number of openings formed through the lid is so selected as to cause the agent to volailize at an adequate rate. However, the number of openings becomes short as the ozone filter deteriorates. While a greater number of openings will eliminate such a problem, they bring about another problem that the agent volatilizes more than necessary and is, therefore, simply wasted at the initial stage of use.
(4) A container body made of polypropylene is commercially available and predominant today. This kind of container body withstands heat and, therefore, allows the open end thereof to be fully sealed by aluminum foil or similar sealing member under the application of heat and pressure at flanges thereof which surround the open end. The agent container with such a container body, however, is not desirable from safety standpoint. Specifically, when an accident such as an ignition occurs in the image forming equipment, especially the exhaust section thereof, the sealed portion is apt to soften or even break to cause the agent to leak therethrough and burn. The container body, therefore, should preferably be made of metal, but such a container body cannot be sealed by heat and pressure. When the container body is made of metal, the open end thereof is usually sealed by the adhesion of a two-sided adhesive tape to the flanges or the application of adhesive thereto. Nevertheless, the adhesion of the flanges of the container body and the sealing member is not sufficient since the container body is made of metal. Regarding two-liquid type epoxy-based adhesive, for example, although the adhesion is sufficient in the initial stage, the agent turns out to be a solvent with the lapse of time and thereby weakens the adhesion, causing the sealing member to come off. In this case, the agent leaks little since the adhesive exhibits good surface contact. While a two-sided adhesive tape exerts a strong adhering force, it cannot prevent the agent from leaking since its surface contact is poor.
(5) The equipment with the conventional ozone removing device is capable of removing a substantial part of ozone brought to the exhaust section thereof. However, ozone entered, for example, the space between the side wall and the front cover of the equipment cannot be removed and stays there. This part of ozone is undesirably released to the atmosphere when the front cover of the equipment is opened.